diff --git a/lib/nexusmods/Cargo.toml b/lib/nexusmods/Cargo.toml
new file mode 100644
index 0000000..93dbd78
--- /dev/null
+++ b/lib/nexusmods/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "nexusmods"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+lazy_static = "1.4.0"
+reqwest = { version = "0.11.14" }
+serde = { version = "1.0.152", features = ["derive"] }
+serde_json = "1.0.94"
+thiserror = "1.0.39"
+time = { version = "0.3.20", features = ["serde"] }
+tracing = "0.1.37"
+url = "2.3.1"
+
+[dev-dependencies]
+tokio = { version = "1.26.0", features = ["rt", "macros"] }
diff --git a/lib/nexusmods/src/lib.rs b/lib/nexusmods/src/lib.rs
new file mode 100644
index 0000000..c8ea2a6
--- /dev/null
+++ b/lib/nexusmods/src/lib.rs
@@ -0,0 +1,132 @@
+use std::convert::Infallible;
+
+use lazy_static::lazy_static;
+use reqwest::header::{HeaderMap, HeaderValue, InvalidHeaderValue};
+use reqwest::{Client, Url};
+use serde::ser::SerializeTuple;
+use serde::{Deserialize, Serialize};
+use thiserror::Error;
+use time::OffsetDateTime;
+
+// TODO: Add OS information
+const USER_AGENT: &str = concat!("DTMM/", env!("CARGO_PKG_VERSION"));
+const GAME_ID: &str = "warhammer40kdarktide";
+
+lazy_static! {
+    static ref BASE_URL: Url = Url::parse("https://api.nexusmods.com/v1/").unwrap();
+    static ref BASE_URL_GAME: Url =
+        Url::parse("https://api.nexusmods.com/v1/games/warhammer40kdarktide/").unwrap();
+}
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error("HTTP error: {0:?}")]
+    HTTP(#[from] reqwest::Error),
+    #[error("invalid URL: {0:?}")]
+    URLParseError(#[from] url::ParseError),
+    #[error("failed to deserialize '{error}': {json}")]
+    Deserialize {
+        json: String,
+        error: serde_json::Error,
+    },
+    #[error(transparent)]
+    InvalidHeaderValue(#[from] InvalidHeaderValue),
+    #[error("this error cannot happen")]
+    Infallible(#[from] Infallible),
+}
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+#[derive(Clone, Debug, Deserialize)]
+pub struct UpdateInfo {
+    pub mod_id: u64,
+    #[serde(with = "time::serde::timestamp")]
+    pub latest_file_update: OffsetDateTime,
+    #[serde(with = "time::serde::timestamp")]
+    pub latest_mod_activity: OffsetDateTime,
+}
+
+#[derive(Copy, Clone, Debug)]
+pub enum UpdatePeriod {
+    Day,
+    Week,
+    Month,
+}
+
+impl Default for UpdatePeriod {
+    fn default() -> Self {
+        Self::Week
+    }
+}
+
+impl Serialize for UpdatePeriod {
+    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        let mut tup = serializer.serialize_tuple(2)?;
+        tup.serialize_element("period")?;
+        tup.serialize_element(match self {
+            Self::Day => "1d",
+            Self::Week => "1w",
+            Self::Month => "1m",
+        })?;
+        tup.end()
+    }
+}
+
+pub struct Api {
+    client: Client,
+}
+
+impl Api {
+    pub fn new(key: String) -> Result<Self> {
+        let mut headers = HeaderMap::new();
+        headers.insert("accept", HeaderValue::from_static("application/json"));
+        headers.insert("apikey", HeaderValue::from_str(&key)?);
+
+        let client = Client::builder()
+            .user_agent(USER_AGENT)
+            .default_headers(headers)
+            .build()?;
+
+        Ok(Self { client })
+    }
+
+    #[tracing::instrument(skip(self))]
+    pub async fn mods_updated(&self, period: UpdatePeriod) -> Result<Vec<UpdateInfo>> {
+        let url = BASE_URL_GAME.join("mods/updated.json")?;
+
+        let res = self
+            .client
+            .get(url)
+            .query(&[period])
+            .send()
+            .await?
+            .error_for_status()?;
+
+        tracing::trace!(?res);
+        let json = res.text().await?;
+
+        serde_json::from_str(&json).map_err(|error| Error::Deserialize { json, error })
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::Api;
+
+    fn make_api() -> Api {
+        let key = std::env::var("NEXUSMODS_API_KEY").expect("'NEXUSMODS_API_KEY' env var missing");
+        Api::new(key).expect("failed to build API client")
+    }
+
+    #[tokio::test]
+    async fn mods_updated() {
+        let client = make_api();
+        client
+            .mods_updated(Default::default())
+            .await
+            .expect("failed to query 'mods_updated'");
+    }
+}